Researchers used electronic dental anesthesia (EDA) to numb the gums of 15 children aged 2 to 4 during the injection of a local anesthetic. EDA was administered after each child had received sedatives to calm him or her. During the injection, EDA significantly reduced moving and crying and also minimized usual heart rate and blood pressure changes associated with injections, compared to a control group of 15 children whom did not receive EDA.

"An injection can evoke a very strong physiologic and emotional response, even in a sedated child," said Stephen Wilson, co-author of the study and a professor of pediatric dentistry at Ohio State University. "EDA was somewhat effective in helping children cope with an injection."

The research appeared in a recent issue of the journalAmerican Academy of Pediatric Dentistry.

The EDA is a battery-operated device that sends electrical impulses through a finger pad that the dentist holds against the tissue surrounding the tooth. The EDA -- which produces a pulsating, tingling sensation -- numbs the tissue or distracts the patient so the discomfort of the injection is partially masked.

While EDA is popular among some dentists for adults, Wilson said, it hasn't received widespread use in pediatric dental care. EDA has traditionally been used in periodontal research, and periodontal problems are more common in adults than children. Also, the EDA finger probe that is placed against the soft tissue is rather large for a child's mouth.

"Children have little lips and mouths, which sometimes makes it difficult to place the electrodes on the gums," Wilson said.

Also, there had never been a study looking at EDA while a patient is under sedation. "Whenever kids are sedated, the one stimulus that really gets them excited is the injection," he said. "It's the injection in the upper front part of the mouth that seems to be the most painful."

The children in this study had what dentists call "baby bottle syndrome" -- cavities, usually on the front teeth, that result from direct exposure to the sweetened liquids a child drinks frequently.

Wilson and his colleagues divided 30 children aged 24 to 48 months into two groups. The researchers turned the EDA device on to treat half of the children, while in the other group, the EDA device was turned off. Each child was given an oral sedative 60 minutes before dental treatment began.

"Very young children are typically sedated because they don't have good coping skills when it comes to dental treatments like having a cavity filled," Wilson said.

Each patient also received the anesthetic nitrous oxide -- also known as laughing gas. The EDA finger pad was placed on the gums five minutes later. A dental assistant increased the current every 20 seconds for a minimum of two minutes before Xylocaine, a local anesthetic, was injected into the gum. The EDA finger pad was removed once the Xylocaine was administered.

"The EDA was no longer needed once the local anesthetic was administered," Wilson said.

The researchers videotaped each child during the procedure to assess four behaviors: quiet; crying; movement; and struggling with crying. They found that the children receiving the activated EDA cried and moved less frequently than those who didn't receive it.

The researchers also compared the physiologic changes of each group. The heart rates and blood pressures of the children not receiving EDA treatment increased with the injection of Xylocaine by an average of 8 percent and 10 percent, respectively. The heart rates and blood pressures of the children receiving the EDA decreased by 2 percent and 3 percent respectively.

"Some children were not aroused to the extent that crying and struggling dominated their behavior during the procedure," Wilson said. "But even when a person is lightly sleeping, the body knows when pain is present. We would still see a rise in heart rate during a painful stimulus."

"While the changes in both blood pressure and heart rates were not outside the normal limits for children with or without the presence of EDA, the degree of discomfort seemed to be more controlled with EDA," Wilson said. "Administering a local anesthetic alone can increase the heart rate by as much as 40 or 50 beats per minute in children."

The 3M company donated the EDA device.

Wilson co-authored the study with Luz de Lourdes Molina, a dentist in Reno, Nev.; James Preisch, an assistant clinical professor of pediatric dentistry at Ohio State; and Joel Weaver, an associate professor of dentistry at Ohio State.

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